react-native/ReactCommon/fabric/events/EventEmitter.h

70 lines
1.8 KiB
C++

/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#pragma once
#include <memory>
#include <mutex>
#include <folly/dynamic.h>
#include <fabric/events/EventDispatcher.h>
#include <fabric/events/primitives.h>
namespace facebook {
namespace react {
class EventEmitter;
using SharedEventEmitter = std::shared_ptr<const EventEmitter>;
/*
* Base class for all particular typed event handlers.
* Stores `InstanceHandle` identifying a particular component and the pointer
* to `EventDispatcher` which is responsible for delivering the event.
*/
class EventEmitter:
public std::enable_shared_from_this<EventEmitter> {
/*
* We have to repeat `Tag` type definition here because `events` module does
* not depend on `core` module (and should not).
*/
using Tag = int32_t;
public:
static std::recursive_mutex &DispatchMutex();
EventEmitter(const EventTarget &eventTarget, const Tag &tag, const std::shared_ptr<const EventDispatcher> &eventDispatcher);
virtual ~EventEmitter() = default;
/*
* Indicates that an event can be delivered to `eventTarget`.
* Callsite must acquire `DispatchMutex` to access those methods.
*/
void setEnabled(bool enabled) const;
bool getEnabled() const;
protected:
/*
* Initates an event delivery process.
* Is used by particular subclasses only.
*/
void dispatchEvent(
const std::string &type,
const folly::dynamic &payload = folly::dynamic::object(),
const EventPriority &priority = EventPriority::AsynchronousBatched
) const;
private:
EventTarget eventTarget_;
Tag tag_;
std::weak_ptr<const EventDispatcher> eventDispatcher_;
mutable bool enabled_; // Protected by `DispatchMutex`.
};
} // namespace react
} // namespace facebook